Polyolefin nanocomposites materials

ABSTRACT

A polyolefin nanocomposite material comprising the following components:
         (A) a crystalline or semi-crystalline polyolefin resin; and   (B) a nanosized mineral filler comprising or substantially consisting of a hydrotalcite, wherein the amount of the hydrotalcite is from 0.02 to 6 parts by weight per 100 parts by weight of the nanocomposite material, and the ratio MFR (1)/MFR (2) of the melt flow rate value MFR (1) of component (A) to the melt flow rate value MFR (2) of the polyolefin nanocomposite material is of at least 1.02,   characterized in that
           the said polyolefin nanocomposite material includes a compatibilizer   the dispersion of the mineral filler (B) and compatibilizer in the polyolefin resin is produced at shear mixing rates from 30 to 300 sec −1 ,

This application is the U.S. national phase of International ApplicationPCT/EP2008/063819, filed Oct. 15, 2008, claiming priority to EuropeanPatent Application 07121629.5 filed Nov. 27, 2007, and the benefit under35 U.S.C. 119(e) of U.S. Provisional Application No. 61/005,731, filedDec. 7, 2007; the disclosures of International ApplicationPCT/EP2008/063819, European Patent Application 07121629.5 and U.S.Provisional Application No. 61/005,731, each as filed, are incorporatedherein by reference.

The present invention relates to polyolefin nanocomposite materialscomprising a polyolefin and at least one nanosized hydrotalcite mineralfiller and to a process for preparing such materials. It also relates toarticles and particularly to fibers and films, sheets and blisters andcups and closures, thermoformed, blow molded and injection molded (IM)articles and pipes formed from said materials.

Particularly, the present invention concerns fibers exhibiting a goodbalance of tenacity, and elongation at break. It also relates to filmsor sheets for thermoforming or blisters exhibiting good barrierproperties, good stiffness and optical properties. It also relates topipes exhibiting improved thermomechanical properties. The polyolefinnanocomposite materials of the present invention exhibit improvedprocessability versus similar nanocomposites based on smectite clays andnanozeolites. Smectite clays include, for example, montmorillonite,saponite, beidellite, hectorite, bohemite and stevensite.

As used herein the term “nanosized filler” means a filler with at leastone dimension (length, width or thickness) in the range from about 0.2to about 500 nanometers.

The definition of fibres includes continuous fibres, staple fibresand/or filaments produced with the spunlaid process and spunbond nonwoven process, tapes and monofilaments.

The polyolefin fibres according to the present invention areparticularly adequate for the use in building and construction, inindustrial, in agricultural, in cloth-like applications and hygieneproducts.

The definition of films includes cast, blown and biaxially orientedfilms, particularly biaxially oriented polypropylene films (BOPP),adequate for the use in food and tobacco packaging and tapes.

The definition of injection molded articles includes injection stretchblow molding articles such as bottles.

Thermoformed articles include all packaging applications rigid andsemi-rigid such as cups and closures.

Composites comprising a polyolefin resin and a nanosized mineral fillerin low amounts are already known. Efforts have been made to increase thecompatibility phenomena between the said two components of differentchemical nature, in order to improve the mechanical, thermal and barrierproperties of the polyolefin nanocomposite material.

For example, U.S. Pat. No. 5,910,523 describes polyolefin nanocompositematerials comprising a semi-crystalline polyolefin and a nanosizedmineral filler wherein the surface of the filler has been modified withfunctionalized compounds.

WO 01/96467 describes polyolefin nanocomposite materials comprising agraft copolymer. The preparation of the graft copolymer is carried outin the presence of an organoclay so that a significant improvement inthe mechanical properties of the products is achieved. The polyolefincomposite materials used for fibres up to now, however, failed toprovide polyolefin fibres with the previously said balance ofperformances. The most serious problem presented by the prior artnanocomposite materials in fiber application is that they are spun withdifficulty.

The present invention overcomes the disadvantages associated with theuse of the above mentioned polyolefin nanocomposite materials in theproduction of fibres, by providing a polyolefin composite materialhaving physical-chemical properties different from those of thecomposite material used up to now.

A great additional advantage of the polyolefin composite material of thepresent invention is that the said material exhibits good drawabilitywith a very good spinning behavior.

It is also known the use of polyolefin composite materials for filmproduction. The main draw back for these films is that they areparticularly prone to breakages as in the European Patent n. 0659815where the filler particles content is from 10 to 30% wt and have anaverage diameter ranging from about 0.5 to 40 μm. It is equally wellknown that the addition of a filler can produce voids that wouldincrease permeability of the film if not filled with waxes as in theInternational Patent Application WO9903673. Thus the addition of afiller is expected to produce voids, brittleness and opaqueness of thefilm thereof.

When the filler is a nanosized filler it is expected to have the sameeffects. Particularly for bioriented films, it is still difficult toobtain a good dispersion of the nanosized filler avoiding the formationof gels or film breakages.

Films produced with the polyolefin composite material of the presentinvention surprisingly exhibits usual processing behavior, very goodoptical and physical-mechanical properties and improved barrierproperties.

When adding a filler or a nanosized filler (nano-filler) such as a clayof the montmonrillonite or bohemite families to a polyolefin compositiona reduction in processability is expected due to an increase of theviscosity of the composition produced by the addition of the filler ornano-filler.

With the fillers of the present invention it was surprisingly found thatthe processability is improved versus similar filled or nano-filledmaterials. Shorter cycle time is possible at equal temperature or lowertemperature of operation is possible for equal cycle time. This, can becorrelated with a nucleating effect of the hydrotalcite in blend withpolyolefins. In this respect, a further use is envisaged for of thehydrotalcite of the present invention as nucleating agent in blend withpolyolefins in amounts from 0.02 to 1 parts by weight of polyolefinblend. It is known that nucleation centers, increasing the temperatureat which the polymer crystallizes and solidifies, thereby reduce cycletime and increase productivity particularly for moulding applications.An higher Tc is measured with the addition of the hydrotalcitenano-filler of the present invention and higher Heat DeflectionTemperature (HDT) is also observed linked with a better temperatureresistance of the material. An increase of more than 5° C. is observedin presence of hydrotalcite in the amounts of the present invention.Thus, the hydrotalcite nano-filler of the present invention combines theadvantage of a nucleating agent with that of a nano-filler which isdesired for applications like medical sterilized items, food packagingin contact with hot water, industrial items exposed to temperatures upto 120° C.

It is known the use of hydrotalcite (basic aluminum magnesium carbonate)as a neutralization agent in polypropylene or polyethylene compositionsas anti-acid neutralizing chlorine residues coming from Ziegler-Nattacatalysts. The U.S. Pat. No. 6,270,209 discloses the neutralizing effectbut remains silent on the nucleating effect. Indeed, the compositiondisclosed also comprise sorbitol derivatives as nucleating agent. Thehydrotalcite is used in small amounts, specifically in the range of0.005 to 1.5 weight percent of the polypropylene or polyethylenecompositions. U.S. Pat. No. 4,611,024 discloses the use of hydrotalcitesin polypropylene polymers as enhancer of the clarifying-nucleatingeffect of alditols (Millad). The hydrotalcite is used in a very smallamount, specifically in the range of 0.01 to 0.5 weight percent,preferably about 0.02 to 0.15 weight percent based on the weight of thepolymer. Hydrotalcites are also known in the art for use as inhibitor ofultraviolet thermal degradation of thermoplastic resins (other thenolefinic) in Miyata et al U.S. Pat. No. 4,299,759 (Nov. 10, 1981). It isalso known the use as conventional fillers in high amounts in polymercompositions such as and WO0190235.

WO03059917 (Sunoco) disclose the preparation of synthetic hydrotalcytesand their use for the preparation of blends with polyolefins andmaleated polyolefin. The self-exfoliation of the hydrotalcite isobtained in a slurry further mixed and heated with the polymer to obtaindispersion of the hydrotalcite present in amounts of 3% or more in theslurry.

The international patent application WO 2006/131450 discloses the use oflayered minerals, particularly of layer silicates, in nanofilledpolyolefin with a valuable balance of properties. A drawback of theknown materials is the organic pre-treatment of the nanosized fillerthat is required for obtaining exfoliation and nano-dispersion of thefiller in the polymeric matrix that produces the desired properties ofthe nanocomposite. As a consequence of the organo-modification polymernanocomposites based on organo-clay materials are not suitable for foodcontact.

There is a continuous demand of new polyolefin materials for fibers andfilms, sheets and thermoformed, blow molded and injection molded (IM)articles such as blisters and cups and closures and bottles, exhibitingimproved balance of properties and further suitable for food contact.

Therefore, the present invention provides a polyolefin nanocompositematerial comprising the following components:

(A) a crystalline or semi-crystalline polyolefin resin; and(B) a nanosized mineral filler comprising or substantially consisting ofa hydrotalcite,wherein the amount of the hydrotalcite is from 0.02 to 6, preferablyfrom 0.03 to 3, more preferably from 0.05 to 1 parts by weight per 100parts by weight of the nanocomposite material, and the ratio MFR (1)/MFR(2) of the melt flow rate value MFR (1) of component (A) to the meltflow rate value MFR (2) of the polyolefin nanocomposite material is ofat least 1.02, preferably from 1.02 to 1.5, characterized in that

-   -   the polyolefin nanocomposite material includes a compatibilizer,        and    -   the dispersion of the mineral filler and compatibilizer in the        polyolefin resin is produced at shear mixing rates from 30 to        300 sec⁻¹, preferably from 30 to 200 sec⁻¹; more preferably from        30 to 150 sec⁻¹

The composite material of the present invention typically exhibits thefollowing properties:

-   -   an increase of the flexural elastic modulus of from at least 1        to 40%, preferably from 10% to 40% with respect to the value        measured on component (A);    -   an increase of heat distortion temperature of from 5 to 25° C.,        preferably from 10 to 25° C., with respect to the value measured        on component (A);    -   an increase of crystallization temperature (Tc) of from 1 to 15°        C., preferably from 10 to 15° C., with respect to the value        measured on component (A). Particularly, the Tc of the        composition is higher than 115° C. when the component (A) is a        polypropylene homopolymer;    -   an increase of Heat Distorsion Temperature (HDT) of at least 10°        C., preferably at least 15° C. with respect to the value        measured on component (A);    -   an increase of gas barrier properties of from at least 5 to 40%,        preferably from 10 to 40% with respect to the value measured on        component (A);    -   MFR(2) values of from 1 to 800 dg/min, preferably from 1.5 to 40        dg/min.

Component (A), namely the starting polyolefin resin matrix, ispreferably a propylene polymer that is either a propylene homopolymer oran heterophasic copolymer or a random interpolymer of propylene with anα-olefin selected from ethylene and a linear or branched C₄-C₈ α-olefin,such as copolymers and terpolymers of propylene. Component (A) can alsobe a mixture of the said polymers, in which case the mixing ratios arenot critical. Preferably, the α-olefin is selected from the groupconsisting of ethylene, 1-butene, 1-pentene, 1-hexene, 1-heptene,1-octene, 1-nonene, 1-decene and 4-methyl-1-pentene. The preferredamount of comonomer content ranges from 0.5 to 15 wt %. The preferredpolyolefin resin is propylene homopolymer.

The said propylene polymer exhibits a stereoregularity of the isotactictype. The percent by weight of polymer insoluble in xylene at ambienttemperature is considered the isotactic index of the polymer. This valuecorresponds substantially to the isotactic index determined byextraction with boiling n-heptane, which by definition constitutes theisotactic index of polypropylene.

The isotactic index of component (A) (measured as above said) ispreferably from 60 to 99%. Particularly, when component (A) is andHomopolymer or random copolymer of propylene the isotactic index ispreferably from 80 to 99%. When the component (A) is an eterophasiccopolymer of propylene the isotactic index is preferably from 60 to 85%.Component (A) can also be advantageously selected from polyethylene andpolybutene-1. Particularly component (A) can be also a LDPE for films,blisters or closures.

When component (A) is polypropylene the crystalline or semi-crystallinepolyolefin resin has an insolubility in xylene at ambient temperature,namely about 25° C., higher than 55 wt %. Component (A) has a melt flowrate value preferably of from 1 to 50 g/10 min. The polyolefinnanocomposite can also undergo chemical degradation with peroxides toincrease the melt flow rate. When component (A) is polyethylene it has amelt flow rate value preferably of from 0.1 to 10 g/10 min. Whencomponent (A) is polybutene-1 it has a melt flow rate value preferablyof from 0.2 to 50 g/10 min.

The melt flow rate (MFR) values are measured according to theappropriate ISO 1133 method, in particular according to ISO method 1133at 230° C., 2.16 kg for propylene polymers, and according to ISO method1133 at 190° C., 2.16 kg for butene-1 or ethylene polymers. The saidpolyolefin resin is prepared by polymerization of the relevant monomersin the presence of a suitable catalyst such as a highly stereospecificZiegler-Natta catalyst or metallocene catalyst. In particular it can beobtained by low-pressure Ziegler-Natta polymerization for example withcatalysts based on TiCl₃, or halogenated compounds of titanium (inparticular TiCl₄) supported on magnesium chloride, and suitableco-catalysts (in particular alkyl compounds of aluminium).

Component (B), namely the layered nanosized mineral filler, is ahydrotalcite.

The general formula of hydrotalcites used in this patent is:

Mg_(2x)Al₂(OH)_(4x+4)CO₃ .nH2O

Were: x>0 and n>0

The hydrotalcite used for the preparation of the nanocomposite materialsof the present invention generally comprise an organic componentfraction that partially substitute CO₃ ²⁻ or OH⁻ anions on thesuperficial layers and also in internal layers.

When the hydrotalcite undergoes appropriate organic treatment theformula can be represented by:

Mg_(2x)Al₂(OH)_((4x+4)−z1)(CO₃)_(1−z2)(A^(m−))_(z) .nH2O

Were: x>0 and “(z)×(m)=z1+2 z2” and n>0 and A=organic anion having avalence of m.

The amount of organic component fraction can vary widely, and could bein the range from 0.5% to 45% by weight, preferably from 20% to 45% byweight and can be expressed in terms of anionic exchange capacity (AEC)ranging from 0.5 to 6 milliequivalents per gram. All the above-mentionedamounts related to the weight of the layered nanosized mineral fillerare based on the dehydrated form.

The organic component fraction is the anionic part of an anionictensioactive or more generally an organic anion of a Metal organic salt(MeA). MeA increases the interlayer distance between the differentlayers of the filler improving the hydrotalcite dispersion in thepolymer matrix.

The organic anions can be selected from the families of conjugated basesof organic acids (HA). Examples, not exhaustive, of suitable organicacids are: carboxylic acids, fatty acids, sulfonic acids, phosphonicacids, and sulfate acids and it is possible to use also a combination ofthose anions.

Preferred are anions of organic substance approved for food contact inpolymers like: Stearic acid, Erucic acid, Oleic acid, Palmitic acid,Laurilic acid, Benzoic acid, Rosin acid, Tartaric acid, Sebacic acid andAdipic acid anions.

The compatibilizer is added to better disperse the mineral filler intothe polyolefin resin. Preferred compatibilizer are modified polyolefinssuch as polyolefin copolymers comprising polar monomers and polyolefinsgrafted with grafting agents comprising polar groups such as thosedisclosed in the patent EP 0747322 (Toyota). In the present inventionthe grafting agents are preferably selected from those containing atleast one functional group selected from carboxylic groups and theirderivatives, such as anhydrides. The aforesaid polar monomers with oneor more functional groups are preferably selected in the groupcomprising: vinyl acetate, acrylic acid, butyl acrilate, metil metaacrilate, meta acrylic acid and olefinic polar monomers.

Particularly preferred as grafting agents are anhydrides of anunsaturated dicarboxylic acid, especially maleic anhydride, itaconicanhydride, citraconic anhydride and tetrahydrophthalic anhydride,fumaric anhydride, the corresponding acids and C₁-C₁₀ linear andbranched dialkyl esters of said acids. Maleic anhydride is preferred.More particularly preferred are grafted copolymers where the backbonepolymer chain is a polymer of an olefin selected from ethylene and/orC₃-C₁₀ α-olefins.

The backbone polymer chain of the modified polyolefin acting as acompatibilizer is preferably made up of olefin(s) monomers that can besame as or different from those of component (A).

The grafting agents are generally grafted on the backbone of the saidpolyolefin to be modified in amounts ranging from 0.4 to 1.5% by weightwith respect to the total weight of the grafted polyolefin.

Comparable amounts of polar monomers in free form can also be present inaddition.

An example of suitable graft copolymer is the polypropylene-g-maleicanhydride.

The polar monomers are present in the polymer chain of the modifiedpolyolefin in amount from 5 to 25% wt with respect to the total weightof the modified polyolefin copolymer.

An example of suitable copolymer comprising polar monomers is anethylene vinyl acetate copolymer (EVA).

The compatibilizer is preferably used in amounts ranging from 0.02 to10% by weight, preferably from 0.05 to 7 wt %, more preferably from 0.05to 2 wt % with respect to the weight of the nanocomposite.

In fiber application low contents of compatibilizer are preferred; infact particularly good results are obtained with amounts of graftedpolyolefin in the range from 0.1 and 1 wt %, particularly from 0.2 to0.5 wt % with respect to the weight of the nanocomposite.

Further components present in the polyolefin nanocomposite material ofthe present invention are additives commonly employed in the art, suchas antioxidants, anti-acids, light stabilizers, heat stabilizers,antistatic agents, flame retardants, fillers, clays, nucleating agents,pigments, anti-soiling agents, photosensitizers.

A further embodiment of the present invention is a process for thepreparation of the said polyolefin nanocomposite material.

The polyolefin nanocomposite material according to the present inventionis prepared by mechanically blending polyolefin component (A), component(B) and the compatibilizer and optionally further components. Thenano-filler component (B) can be blended in pure (undiluted) form withthe polyolefin component (A) in the presence of a compatibilizer (onestep process) or, preferably, as part of an intercalated masterbatch(two step process); in such a case, component (B) is previouslydispersed in a polymer resin (A′), that can be same as or different frompolyolefin component (A), in presence of the compatibilizer. Themasterbatch thus prepared is then blended with the polymer component(A). The nanocomposite composition according to the present inventioncan be prepared by a melt mixing process using conventional equipments,such as an extruder, like a Buss extruder, or a single or a twin screwextruder with length/diameter ratio from 18 or more, preferred from 18to 40, or a mixer, like a Banbury mixer. Preferred extruders areequipped with screws able to generate low values of shear stress.Particularly with such extruders lower values of the length/diameterratio are not excluded; in fact particularly good results are obtainablealready with length/diameter ratio from 15 or more.

The two step process of producing the polyolefin nanocomposite materialaccording to the present invention comprises at least the two followingsteps:

1) preparing an intercalated (partially exfoliated) masterbatch bymixing a polyolefin resin (A′) that can be the same as component (A) ordifferent, with a mineral filler (B) in presence of a compatibilizer;and

2) mixing the intercalated masterbatch prepared in step (1) with thepolyolefin resin component (A).

The nanosized filler is preferably added to the polyolefin resin when itis in the molten state. In an extruder the mineral filler is added witha feeder positioned after the melting of the polymer.

The above-mentioned other additives can be added, in a two step process,during either step (1), step (2) or both. The compatibilizer is addedduring step (1) before adding the mineral filler (B). Preferably thecompatibilizer and other additives are added in step (1) to thepolyolefin resin when it is still in the solid state.

The said process uniformly disperses the mineral filler in thepolyolefin matrix and leads to nanocomposites having a high degree ofexfoliation of the mineral filler (B).

The amount of layered nanosized mineral filler in dehydrated form ispreferably from 2 to 40% by weight, more preferably from 2 to 26% byweight with respect to the total weight of the masterbatch. Thecompatibilizer is present in amounts preferably from 2 to 40% by weight,more preferably from 2 to 26% by weight with respect to the total weightof the masterbatch obtained in step (1). The intercalated masterbatchtypically exhibit an increase of flexural elastic modulus of from 10 to100% with respect to the starting polyolefin resin Preferred aspre-exfoliating polyolefin resin (A′) for the preparation of theintercalated (partially exfoliated) masterbatch in step 1 is a butene-1polymer having a melt flow rate value preferably of from 0.2 to 50 g/10min (190/2.16, ISO1133) preferably of from (3 to 20 g/10 min), and amelting temperature of from 90 to 130° C. preferably of from (110 to128° C.). Preferred butene-1 polymers for the preparation of themasterbatch in step 1 are homo or copolymers of butene-1 with one ormore α-olefins as comonomers selected from ethylene, propylene and alinear or branched C5-C8 α-olefin. Preferably, the α-olefin comonomer isselected from the group consisting of ethylene, propylene, 1-pentene,1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene and4-methyl-1-pentene. The preferred amount of comonomer content in thebutene-1 copolymer ranges from 0.5 to 15 wt %. Particularly preferredpolyolefin resin (A′) is a butene-1 homopolymer.

The above said process steps (1) and (2) are preferably carried outunder the following conditions:

-   -   shear mixing rate ranging from 30 to 300 sec⁻¹, preferably from        30 to 150 sec⁻¹;    -   a mixing temperature higher than the polymer softening        temperature, in particular of at least 180° C., preferably from        180 to 250° C.;    -   residence time in mixing machine over 80 sec.

Uniform dispersion of the nanosized filler with a high degree ofexfoliation of the said filler in the polyolefin matrix can be obtainedalso with a one step process.

The one step process comprises the addition of the undiluted mineralfiller component (B) directly on the molten polyolefin resin component(A). The compatibilizer and the other additives, that can be optionallyadded, are preferably added to component (A) before the said step ofaddition of the layered mineral filler component (B), when thepolyolefin component (A) is still in the solid state.

The addition of the nano-filler on the molten polymer, both in the onestep and in the two step process, prevents deterioration of the aspectratio of the filler platelets.

The same preferred extrusion conditions, reported for the two stepprocess above, are indicated also for the one step process.

Another embodiment of the present invention is a fibre made from theabove mentioned polyolefin nanocomposite material, thus comprising orsubstantially consisting of the said material. The amount of layerednanosized mineral filler in the polyolefin nanocomposite material forfibers is preferably from 0.05 to 2% by weight, more preferably from 0.1to 1% by weight, even more preferably from 0.2 to 0.5% by weight of thenanosized mineral filler in dehydrated form, with respect to the totalweight of the nanocomposite material. Polyolefin nanocomposite materialfor fibers are produced preferably with the two step process. Fibersproduced with the nanocomposite material of the present invention can beproduced by any conventional process included bulk continuous filamentand Spunbond non woven. Thus, another further embodiment of the presentinvention is a non-woven fabric comprising the previously said fibres.

The unstretched filaments (fiber) according to the present inventiontypically exhibit the following balance of properties: a tenacity valuehigher than 22 cN/tex and an elongation at break value higher than 200%.

The polyolefin material used for the production of nanocompositematerials for fibers has a M _(w)/ M _(n) value, measured by GPC,typically ranging from 2 to 10, and MFR ranging from 8 to 800 g/10 min,

A still further embodiment of the present invention is a film,bioriented, blown or cast made from the above mentioned polyolefinnanocomposite material, thus comprising or substantially consisting ofthe said material.

Particularly preferred are BOPP films and polyethylene blown films thatwhen produced according to the present invention typically exhibitsimproved barrier properties with respect to gases such as O₂, CO₂ andwater vapour. Particularly an improvement of O₂ barrier activity of atleast 20% is observed with PP homopolymers with respect to the referencematerial without nanosized filler.

Instead, with films produced with LDPE nanocomposite, barrierimprovements from 5 to 15% are observed.

Stretchability of the films according to the invention does not getworse for the addition of the nanosized hydrotalcite with respect to thereference material at the temperature of the stretching process. Alsothe optical properties, particularly Haze and Gloss, do not get worsefor the addition of the nanosized hydrotalcite with respect to thereference material.

The polyolefin material used for the production of nanocompositematerials for BOPP processes typically has a M _(w)/ M _(n) value from 4to 8, and an MFR value from 1.5 to 5 g/10 min. The amount of nano-fillercomponent (B) in nanocomposites for BOPP application according to theinvention is typically from 0.5 to 3% by weight of nanosized mineralfiller in dehydrated form, with respect to the total weight of thenanocomposite material. The amount of nano-filler component (B) innanocomposites for LDPE film application according to the invention istypically from 0.3 to 6% by weight of nanosized mineral filler indehydrated form, with respect to the total weight of the nanocompositematerial.

A still further embodiment of the present invention is a pipe, made fromthe above mentioned polyolefin nanocomposite material, thus comprisingor substantially consisting of the said material. The polyolefinmaterial used for the production of nanocomposite materials for pipetypically a polybutene-1 homopolymer or copolymers of butene-1 an atleast one other alfa-olefin. When the polyolefin material is a copolymerof butene-1 with ethylene, typically the amount of ethylene comonomer isfrom 0.3 to 2% wt preferably from 0.5 to 1% with respect to the weightof the copolymer. The amount of nanosized mineral filler component (B)in nanocomposites for pipe application according to the invention istypically from 0.1 to 1.5, preferably from 0.2 to 1.2% by weight ofnanosized mineral filler in dehydrated form, with respect to the totalweight of the nanocomposite material. The improvement ofphysical-mechanical properties exhibited by the nanocomposite,particularly the improvement of Flexural Modulus brings to improvementof creep resistance and the possibility of down gauging the use ofmaterial e.g. the thickness of the pipe can be reduced withoutcompromising performance.

Another further embodiment of the present invention is a Polyethylenefilm or a sheet for thermoformed blisters or an injection molded articlefor cups and closures applications and blown bottles.

The particulars are given in the following examples, which are given toillustrate, without limiting, the present invention.

The following analytical methods have been used to determine theproperties reported in the detailed description and in the examples.

-   -   Melt Flow Rate (MFR): According to ISO method 1133 (230° C.,        2.16 kg, for polypropylene) if not differently specified.    -   Fractions soluble and insoluble in xylene at 25° C.: 2.5 g of        polymer are dissolved in 250 ml of xylene at 135° C. under        agitation. After 20 minutes the solution is allowed to cool to        25° C., still under agitation, and then allowed to settle for 30        minutes. The precipitate is filtered with filter paper, the        solution evaporated in nitrogen flow, and the residue dried        under vacuum at 80° C. until constant weight is reached. Thus        one calculates the percent by weight of polymer soluble and        insoluble at room temperature.    -   Flexural elastic modulus: According to ISO 178.    -   Density: According to ISO 1183.    -   Heat Distortion Temperature (HDT): According to ISO 75.    -   Tensile properties (Tensional Elastic Modulus, Stress at Break,        Elongation at Break, Stress at Yield, Elongation at Yield):        According to ISO 527-1,-2.    -   Crystallization Temperature Tc: according to ISO 11357, via DSC        (2nd run at 20° C./min cooling)    -   Titre of filaments: from a 10 cm long roving, 50 fibres are        randomly chosen and weighed. The total weight of the said 50        fibres, expressed in mg, is multiplied by 2, thereby obtaining        the titre in dtex.    -   Tenacity and Elongation (at break) of filaments: from a 500 m        roving a 100 mm long segment is cut. From this segment the        single fibres to be tested are randomly chosen. Each single        fibre to be tested is fixed to the clamps of an Instron        dynamometer (model 1122) and tensioned to break with a traction        speed of 20 mm/min for elongations lower than 100% and 50 mm/min        for elongations greater than 100%, the initial distance between        the clamps being of 20 mm. The ultimate strength (load at break)        and the elongation at break are determined.    -   The tenacity is derived using the following equation:

Tenacity=Ultimate strength (cN)10/Titre (dtex).

-   -   Film Haze: According to ASTM D-1003.    -   Film Gloss According to ISO 2813.    -   Film Permeability (gas transmission rate): According to ASTM        D1434-82 (2003).

EXAMPLE 1 AND COMPARATIVE EXAMPLE 1 (1c)

In a monoscrew Buss 70 extruder having a length/diameter ratio of 17 ablend (intercalated masterbatch) was prepared by mixing the followingcomponents:

1) 95 wt % of a polyolefin matrix consisting of an isotactic propylenehomopolymer (MFR 12) produced by polymerizing propylene in the presenceof a Ziegler-Natta catalyst, having a solubility in xylene at 25° C. ofabout 3% wt;2) 2.5 wt % of an organo-hydrotalcite (component (B)) marketed with thetrademark PERKALITE F100 by AKZO NOBEL, containing a saturated fattyacid as modifier; and3) 2.5 wt % of a maleic anhydride-g-polypropylene (compatibilizer)having 0.7 wt % of maleic anhydride grafted on the polypropylene.

The extrusion was carried out adding component 3 to component 1 when itis still in the solid state and component (2) to the melt of component(1) and (3) in the extruder under the following conditions:

-   -   extrusion temperature: 220° C.;    -   residence time in the extruder: 1.5 min;    -   shear mixing: 100 sec⁻¹.

The comparative example 1 (1c) is the reference material (polyolefinmatrix (1)) without filler and compatibilizer.

Table 1 reports the amounts of component 1 and 2 and of the filler andcompatibilizer in the final polyolefin nanocomposite materials, and theproperties of the materials determined on injection molded samplesprepared according to ISO 294.

TABLE 1 Examples 1C 1 Polyolefin homopolymer- 100 95 component (A), wt %Mineral filler, wt %*^(—)component (B) 2.5 Compatibilizer, wt % 2.5 MFRof polyolefin component (A) 13 (MFR (1)) dg/min MFR of polyolefinnanocomposite material 10.4 (MFR (2)), dg/min MFR (1)/MFR (2) ratio —1.25 Properties of the nanocomposite material Flexural elastic modulus,MPa 1340 1493 Density, g/ml 0.905 0.915 Heat Distortion Temperature, °C. (0.46 N/mm²) 89 100 Elongation at break*, % >200 >200 Tc (via DSC2^(nd) run 20° C./min cooling) 109 116 Tensional elastic modulus, MPa1335 1520 stress at yield, MPa 33.2 34.1 elongation at yield, % 11 9stress at break, MPa 19.3 20.4 IZOD notched at 23° C., kJ/m² 3.3 3.4*Elongation at break measured with a dynamometer having maximumextension of 200%

EXAMPLE 2-4 AND COMPARATIVE EXAMPLE 2 (2c) Fibers

Step (1): Preparation of the Masterbatch

The blend prepared in example 1 was used as masterbatch in theseexamples.

Step (2) Preparation of the Polyolefin Nanocomposite Material

In the same type of extruder as that used in example (1) polyolefinnanocomposite materials were prepared by mixing in different amounts thefollowing components:

1) an isotactic propylene homopolymer (MFR 28.4) (component (A))produced by polymerizing propylene in the presence of a Ziegler-Nattacatalyst, having a solubility in xylene at 25° C. of about 3% wt andcontaining Irganox B215 conventional stabilizer formulation for fiberscommercialized by CIBA; and2) the blend prepared in example 1.

The extrusion took place under the same conditions as for example (1).

Preparation of the Fibres

The polyolefin nanocomposite material thus obtained was spun in aLeonard pilot plant to prepare continuous fibres. The spinning processwas carried out at a temperature of 280° C. and at a spinning rate of1500 m/min and constant out-put of 0.4 grams/min·hole. Then the fibrewas stretched at a stretching ratio of 1:15, for a final take up speedof 2250 m/min. The maximum spinnability speed was 3900 m/min.

The comparative example 2 (2c) is the reference material (component (A))without filler and compatibilizer processed as the other samples.

Table 2 reports the amounts of component 1 and 2 and of the filler andcompatibilizer in the final polyolefin nanocomposite materials, and theproperties of the materials as such and those of fibres produced withthe polyolefin nanocomposite materials.

TABLE 2 Examples 2C 2 3 4 Process Step (2) Polyolefin homopolymer- 10098 96 88 component (A), pw Masterbatch-blend of example 1, pw 2 4 12Final polyolefin nanocomposite material Mineral filler, wt %* 0.05 0.10.3 Compatibilizer, wt % 0.05 0.1 0.3 MFR of polyolefin component (A)28.4 (MFR (1)) dg/min MFR of polyolefin nanocomposite material 27.4 27.126.5 (MFR (2)), dg/min MFR (1)/MFR (2) ratio — 1.04 1.05 1.09 Propertiesof the nanocomposite material on IM plaques Flexural elastic modulus,MPa 1360 1410 1450 1540 Density, g/ml 0.905 0.906 0.907 0.908 HeatDistortion Temperature (0.45 MPa), ° C. 88 92 97 99 Elongation at break,% 200 250 310 370 Spinning Process Head Temperature ° C. 280 280 280 280spinning rate m/min 1500 1500 1500 1500 Stretching ratio 1:1.5 1:1.51:1.5 1:1.5 Properties of fibres maximum spinnability speed m/min 39003900 3900 3900 Titer, dtex 2.3 2.2 2.15 2.15 Tenacity, cN/tex 23 26 2523 Elongation at break, % 180 220 215 210 *The values of Mineral filler,wt % are calculated with respect to the final nanocomposite materialweight and considering the inorganic plus the organic componentfractions of the mineral filler.

EXAMPLE 5-7 AND COMPARATIVE EXAMPLE 5 (5C) BOPP Films

Step (1): Preparation of the Masterbatch

In a twin-screw extruder having a length/diameter ratio of 27 amasterbatch was prepared by mixing the following components:

1) a polyolefin matrix consisting in an isotactic propylene homopolymerproduced by polymerizing propylene in the presence of a Ziegler-Nattacatalyst, having a solubility in xylene at 25° C. of about 4% wt andcontaining a conventional stabilizer formulation and having a MFR of 1.9(dg/min);2) an hydrotalcite (component (B)); and3) a maleic anhydride-g-polypropylene (compatibilizer) having 0.7 wt %of maleic anhydride grafted on the polypropylene.

The masterbatch a was prepared with an hydrotalcite marketed with thetradename Perkalite F100 by Akzo (F100).

The masterbatches b and c were prepared with a different commercialhydrotalcite marketed with the tradename Perkalite P100S by Akzo(P100S). Perkalite P100S has a higher organic treatment than PerkaliteF100. The grafted PP compatibilizer was not added to the masterbatch b.

The extrusion of the masterbatches was carried out under the followingconditions:

-   -   extrusion temperature: 230° C.;    -   residence time in the extruder: 2 min;    -   shear mixing: 130 sec⁻¹.

Table 3a reports the amounts of component 1, 2 and 3 in themasterbatches.

TABLE 3a Masterbatch a b c Polyolefin homopolymer, pw 65 75 65 Mineralfiller, wt % F100 25 *^(—)component (B) P100S 25 25 Compatibilizer, wt %10 0 10

Step (2) Preparation of the Polyolefin Nanocomposite Material

After the preparation of the masterbatch, in the same type of extruderas that used in step (1), a polyolefin nanocomposite material wasprepared by mixing the following components:

1) 90 parts by weight (pw) of an isotactic propylene homopolymer(component (A)) of the same type as that used for the matrix in themasterbatch; and2) 10 parts by weight of the masterbatch previously prepared.

The extrusion took place under the same conditions as for step (1).

Preparation of the BOPP Film

The polyolefin nanocomposite material thus obtained were compressionmoulded on a CARVER machine at 200° C. to obtain a plaque 1 mm thick and60×60 mm and then have been stretched using TM-Long machine at an oventemperature of 150° C. with a stretching ratio of 7×7 in both directionsto obtain a BOPP film 21-23 μm thick

The comparative example 5 (5c) is the reference material (component (A))without filler and compatibilizer processed as the other samples.

Table 3b reports the amounts of component 1) and 2) the type and amountof nano-filler and compatibilizer in the final polyolefin nanocompositematerial and the properties of the BOPP film produced with thepolyolefin nanocomposite material and comparative reference material.

TABLE 3b Examples 5c 5 6 7 Process Step (2) Polyolefin homopolymer -component (A), pw 100 90 90 90 Masterbatch a, pw — 10 Masterbatch b, pw10 Masterbatch c, pw 10 Final polyolefin nanocomposite material Mineralfiller, wt %* 0 2.5 2.5 2.5 Mineral filler Type — F100 P100S P100SCompatibilizer, wt % 0 1 0 1 MFR of Polyolefin homopolymer (1) 1.9 (MFR(1)) dg/min (on pellet) MFR of polyolefin nanocomposite material — 1.51.4 1.6 (MFR (2)), dg/min (on pellet) MFR (1)/MFR (2) ratio (on pellet)1.3 1.4 1.2 Stretching Process Temperature ° C. 150 150 150 150Properties of the BOPP film Thickness, μm 22 22 19 23 Haze % 0.6 1.4 0.60.6 Gloss 60° % 93 91.3 93 93 Tensional Elastic Modulus, MPa 2370 24702500 2200 Elongation at Break, % 27 15 31 33 Gas Barrier Properties ofthe BOPP film film thickness, μm 22 22 19 23 O₂ Transmission Rate, cc/m²24 h (T = 25° C., RH = 0%) 1942 1362 1504 1442 OTR Normalized at 20 μ,cc/m² 24 h 1765 1238 1583 1254 Barrier improvement vs. Ref. 5c % — 29.917.4 29.0 *The values of Mineral filler, wt % are calculated withrespect to the final nanocomposite material weight and considering theinorganic plus the organic component fractions of the mineral filler.

EXAMPLE 8-10 AND COMPARATIVE EXAMPLES 8 AND 10 (8c-10c) InjectionMoulding

Step (1): Preparation of the Masterbatch

In a twin-screw extruder having a length/diameter ratio of 27 amasterbatch was prepared by mixing the following components:

1) 52 wt % of a polyolefin matrix consisting in an isotactic propylenehomopolymer (MFR 12) produced by polymerizing propylene in the presenceof a Ziegler-Natta catalyst, having a solubility in xylene at 25° C. ofabout 3.5% wt and containing a conventional stabilizer formulation forinjection moulding.2) 20 wt % of an Hydrotalcite marketed with the trademark Pural MG 63 HTby Sasol (MG63HT), containing 2% by weight of organic component(carboxylic fatty acid); and3) 28 wt % of a maleic anhydride-g-polypropylene having 0.7 wt % ofmaleic anhydride grafted on the polypropylene.

The extrusion was carried out under the same conditions of example 1:

-   -   extrusion temperature: 230° C.;    -   residence time in the extruder: 1.5 min;    -   shear mixing: 100 sec-1.

Step (2) Preparation of the Polyolefin Nanocomposite Material

After the preparation of the masterbatch, in the same type of extruderas that used in process step (1) a polyolefin nanocomposite material wasprepared by mixing the following components:

1) 95 wt % of the same isotactic propylene homopolymer (MFR 12) used instep (1) produced by polymerizing propylene in the presence of aZiegler-Natta catalyst, having a solubility in xylene at 25° C. of about3.5% wt and containing a conventional stabilizer formulation forinjection moulding. (component (A))2) 5 wt % of the masterbatch previously prepared in step (1) of thisexample.

The extrusion took place under the same conditions as for step (1).

The comparative example 8 (8c) is the reference material (component (A))without filler and compatibilizer processed as the other samples.

The comparative Example 10 (10C) is prepared for comparison using adifferent nano-filler: Cloisite 15A by Southern Clay Products (C15A),containing 43% by weight of organic component (organic ammonium salt).The sample was prepared with the same procedure of Example 10 andamounts of fillers and compatibilizers as summarized in table 4;

Table 4 reports the amounts of filler and compatibilizer in the finalpolyolefin nanocomposite material for the examples 8-10 and comparativeexample 8c and 10c together with the properties measured on injectionmolded plaques (prepared according to ISO 294).

TABLE 4 Examples 8c 8 9 10 10c Process Step (2) Polyolefin homopolymer -100 95 85 75 75 component (A), pw Masterbatch, pw 0 5 15 25 25 Finalpolyolefin nanocomposite material Mineral filler Type — MG63HT MG63HTMG63HT C15A Mineral filler, wt %* 0 1 3 5 5 Compatibilizer, wt % 1.4 4.27 7 MFR of polyolefin component (A) 11.5 (MFR (1)) dg/min (on pellets)MFR of polyolefin nanocomposite material 10.0 9.8 9.6 7.2 (MFR (2)),dg/min (on pellets) MFR (1)/MFR (2) ratio (on pellets) 1.15 1.17 1.201.60 Characterization of Injection molded specimens (plaques preparedaccording to ISO 294) Flexural Modulus, MPa 1410 1729 1705 1671 2064Stress at Yield, MPa 33.3 34.9 34.4 34.0 33.9 Elongation at Yield, %11.0 7.6 9.4 9.6 8.4 Stress at Break, MPa >24 20.6 >24 >24 18.6Elongation at Break, % >250 180 >250 >250 59 H.D.T 0.46 N/mm², ° C. 90.5110.1 111.9 112.4 108.5 IZOD notched, 23° C., kJ/m² 3.4 3.7 3.6 3.6 3.4*The values of Mineral filler, wt % are calculated with respect to thefinal nanocomposite material weight and considering the inorganic plusthe organic component fractions of the mineral filler.

EXAMPLE 11 AND COMPARATIVE EXAMPLES 11b, 11c Injection Moulding

One Step Process:

In a twin-screw extruder having a length/diameter ratio of 27 ananocomposite material (sample 11, Table 5) was prepared by mixing thefollowing components:

1) 88 parts by weight (pw) of an isotactic propylene homopolymer (MFR12) (component (A)) produced by polymerizing propylene in the presenceof a Ziegler-Natta catalyst, having a solubility in xylene at 25° C. ofabout 3.5% wt and containing a conventional stabilizer formulation forinjection moulding.2) 5% wt % of an hydrotalcite marketed with the tradename Pural MG 61 HTMC by Sasol, containing 15% by weight of organic component (stearicacid); and3) 7 wt % of a copolymer of ethylene with acrilic acid and buthylacrilate (EBA) compatibilizer, having 4 wt % of acrylic acid and 7 wt %of buthyl acrilate copolymerized with polyethylene.

The extrusion was carried out under the following conditions:

-   -   extrusion temperature: 240° C.;    -   residence time in the extruder: 2 min;    -   shear mixing: 150 sec⁻¹.

Reference examples 11b and 11c were prepared with same procedure andamount of fillers and compatibilizer as specified in table 5

EXAMPLE 12, AND COMPARATIVE EXAMPLE 12c

Example 12 with same procedure of example 11 using hydrotalcitePerkalite P1005 from Akzo (PS 100) as nano-filler.

The comparative Example 12 (12c) is prepared for comparison using adifferent nano-filler: Cloisite 15A by Southern Clay Products (C15A),containing 43% by weight of organic component (organic ammonium salt).The sample was prepared with the same procedure of Example 12 andamounts of fillers and compatibilizers as summarized in table 5. Table 5reports the amounts of filler and compatibilizer in the final polyolefinnanocomposite material for the examples 11-12 and comparative examples11b, 11c and 12c together with the properties measured on injectionmolded plaques (prepared according to ISO 294).

TABLE 5 Examples 11b 11c 11 12 12c Final polyolefin nanocompositematerial Polyolefin homopolymer - 100 93 88 88 88 component (A), pwMineral filler Type — — MG61 P100S C15A HTMC Mineral filler, wt %* 0 0 55 5 Compatibilizer, wt % 0 7 7 7 7 MFR of polyolefin component (A) 12 1212 12 12 (MFR (1)) dg/min (on pellets) MFR of polyolefin nanocompositematerial 13 10 9.2 7.5 (MFR (2)), dg/min (on pellets) MFR (1)/MFR (2)ratio (on pellets) 0.92 1.2 1.3 1.6 Characterization of Injection moldedspecimens Flexural Elastic Modulus, MPa 1350 1414 1634 1640 1948 Stressat Yield, MPa 33.1 34.1 35.1 34.5 37.7 Elongation at Yield, % 11.1 9.78.6 8.0 8.3 Stress at Break, MPa 21.2 21.2 26.5 39.1 28.4 Elongation atBreak, % 750 825 62 64 26 H.D.T 0.46 N/mm², ° C. 92 92 111 110 106 Tc(via DSC 2^(nd) run 20° C./min cooling) 107 108 121 120 110 *The valuesof Mineral filler, wt % are calculated with respect to the finalnanocomposite material weight and considering the inorganic plus theorganic component fractions of the mineral filler.

EXAMPLE 13 AND COMPARATIVE EXAMPLE 13 (13c) LDPE Film

One Step Process:

In a twin-screw extruder having a length/diameter ratio of 27 ananocomposite material was prepared by mixing the following components:

1) 98.9 wt % of a polyolefin matrix consisting in a Low density PE(LDPE) produced by high-pressure tubular reactor process (Lupotech Tprocess technology) described in the patent n. EP449092 or EP121756,having a density 0.930 g/cm3 (ISO 1183) and a MFR 0.55 (190° C./2.16 Kg,ISO 1133).2) 0.5% wt % of an organoclay marketed with the trademark hydrotalcitePerkalite F100 from Akzo; and3) 0.5 wt % of a EVA copolymer of ethylene with vinyl acetate having 12wt % of vinyl acetate copolymerized with polyethylene and MFR/E 2.5(190° C., 2.16 Kg) and density of 0.930 g/cm3 (commercialized under thename Elvax 3130 by Du Pont).4) 0.1 of Irganox B215 as conventional stabilizer

The extrusion was carried out under the following conditions:

-   -   extrusion temperature: 200° C.;    -   residence time in the extruder: 2 min;    -   shear mixing: 150 sec⁻¹.

The comparative example 13 (13c) is the reference material (LDPE)without filler and compatibilizer processed as the other samples with aconventional stabilizer.

EXAMPLE 14-16 LDPE Film

Example 13 was repeated except for the amounts of hydrotalcite and EVAthat were changed as reported in Table 6.

Preparation of the LDPE Films

The polyolefin nanocomposite material thus obtained in examples 13-16and comparative 13c, were processed with a monoscrew extruder 55 mmwidth and with a length/diameter (L/D) ratio of 30. The machine was setup to obtain a 500 μm thick blown film at a machine melt temperature of220° C. and a blown up ratio of 1:3 with air temperature of 22° C.:

Table 6 reports the amounts of component 1) and 2) 3) in the finalpolyolefin nanocomposite material and the properties of the filmproduced with the polyolefin nanocomposite material for the examples13-16 and comparative reference material of example 13c together withthe properties measured on injection molded plaques (prepared accordingto ISO 294) and properties of the final LDPE films.

TABLE 6 Examples 13c 13 14 15 16 One step process Polyethylene lowdensity 99.9 98.9 97.9 92.9 89.9 component (A), pw Mineral filler, wt %*0 0.5 1.0 3.5 5.0 Compatibilizer, EVA, wt % 0 0.5 1.0 3.5 5.0 IrganoxB215, wt % 0.1 0.1 0.1 0.1 0.1 MFR of polyolefin component (A) 0.55 0.550.55 0.55 0.55 (MFR (1)) dg/min (on pellets) MFR of polyolefinnanocomposite material 0.51 0.51 0.53 0.54 (MFR (2)), dg/min (onpellets) MFR (1)/MFR (2) ratio (on pellets) 1.08 1.08 1.04 1.02Characterization of compression molded specimens Tensile Modulus at 23°C., MPa 365 375 400 410 422 Tensile Modulus at 60° C., MPa 152 156 157160 163 Stress at Yield, MPa 13.3 12.9 13.7 13.5 12.1 Elongation atYield, % 12.3 12.8 12.7 11.7 11 Stress at Break, MPa 13.6 10.7 11.3 11.012.0 Elongation at Break, % 510 460 485 26 10 Charpy notched 23° C.,kJ/m² 76 59 17 10 8 Charpy notched −20° C., kJ/m² 8.3 6.3 4.6 4.2 3.5Melting Temperature via DSC, ° C. 117.1 117.3 117.6 117.7 118.0 Tc—Crystallization Temp. via DSC, ° C. 102.0 103.3 103.5 103.5 104.3 GasBarrier Properties of the film O₂ Transmission Rate on 500 μm film, 235223 217 214 210 (T = 25° C., RH = 0%) cc/m² · day Barrier improvementvs. Ref. 13c, % — 5.1 7.7 8.9 10.6 *The values of Mineral filler, wt %are calculated with respect to the final nanocomposite material weightand considering the inorganic plus the organic component fractions ofthe mineral filler.

EXAMPLE 17 AND Comparative Example 17c Pipes

One Step Process:

In a mono-screw Buss 70 extruder having a length/diameter ratio of 17 ananocomposite material was prepared by mixing the following components:

1) 99.35 wt % of a polyolefin matrix consisting in a Polybutene (PB-1)produced by liquid monomer solution process (Bulk solution technology)described in the International Patent Application WO2004/000895, havinga density 0.914 g/cm3 (ISO 1183) and a MFR 0.4 (190° C./2.16 Kg, ISO1133), commonly used for pipes applications.2) 0.25% wt % of an organoclay marketed with the trademark hydrotalcitePerkalite F100 from Akzo; and3) 0.25 wt % of a maleic anhydride-g-polypropylene (compatibilizer)having 0.7 wt % of maleic anhydride grafted on the polypropylene andMFR/L 120 (230° C., 2.16 Kg) density 0.930 g/cm3 (commercialized underthe name Polybond 3200 by Crompton).4) 0.15 of Irganox B215 as conventional stabilizer

The extrusion was carried out under the following conditions:

-   -   extrusion temperature: 230° C.;    -   residence time in the extruder: 90 sec.    -   shear mixing: 130 sec⁻¹.

The comparative example 17c is the reference material (1) without fillerand compatibilizer processed as the other samples with a conventionalstabilizer Irganox B215.

EXAMPLE 18-19-20 PB-1 Pipes

Examples 17 was repeated except for the amounts of hydrotalcite andMA-g-PP that were changed as reported in Table 7

Example 20 is equivalent to 18 without compatibilizer.

TABLE 7 Examples 17c 17 18 19 20 One Step Process Polybutene polymer -100 95 85 75 75 component (A), pw Mineral filler Type — F-100 F-100F-100 F-100 Mineral filler, wt %* 0 0.25 0.5 1.0 0.5 Compatibilizer, wt% — 0.25 0.5 1.0 0 MFR of polyolefin component (A) 0.42 (MFR (1)) dg/min(on pellets)(*) MFR of polyolefin nanocomposite material 0.35 0.32 0.280.45 (MFR (2)), dg/min (on pellets)(*) MFR (1)/MFR (2) ratio (onpellets) 1.2 1.3 1.5 0.93 Characterization of compression moldedspecimens Flexural Modulus, MPa 364 433 441 470 376 Stress at Break, MPa34 35 36 37 33 Elongation at Break, % 318 330 345 350 320 H.D.T 0.46N/mm², ° C. 91 101 105 111 94 (*)MFR: 190° C., 2.16 Kg

EXAMPLE 21 Stage (1): Preparation of the Masterbatch

In a mono-screw Buss 70, diameter 70 mm, length/diameter ratio L/D=17, amasterbatch was prepared by mixing the following components:

1) 95 wt % of a polyolefin matrix consisting in a polybutene homopolymer(MFR 4, measured at 190° C., 2.16 Kg) having a melting temperature of127° C., produced by polymerizing butene-1 in the presence of aZiegler-Natta catalyst and containing a conventional stabilizerformulation for fibers; and2) 5 wt % of an organo-hydrotalcite (component (B)) marketed with thetradename Perkalite F100 by AKZO NOBEL, containing a saturated fattyacid as modifier; and3) 5 wt % of a maleic anhydride-g-polypropylene (a suitable one ismarketed with the tradename Polybond 3200, by Chemtura) having 0.7 wt %of maleic anhydride grafted on the polypropylene.

Stage (2) Preparation of the Polyolefin Nanocomposite Material

After the preparation of the masterbatch, in a twin-screw extruderhaving a screw diameter of 27 mm and a length/diameter ratio of 40 apolyolefin nanocomposite material was prepared by mixing the followingcomponents:

1) 94 parts by weight (pw) of an isotactic propylene homopolymer (MFR25.8) having a solubility in xylene at 25° C. of about 3.9% wt, producedby polymerizing propylene in the presence of a Ziegler-Natta catalyst;2) 6 pw of the masterbatch previously prepared.

The extrusion was carried out in stage (1) and (2) in under thefollowing conditions:

-   -   extrusion temperature: 180° C.;    -   residence time in the extruder: 1.5 min;    -   average shear mixing: 100 sec⁻¹.

Preparation of the Fibres

The polyolefin nanocomposite material thus obtained was spun in aLeonard pilot plant to prepare continuous fibres. The spinning processwas carried out at a measured melt temperature of 263° C. (255-260° C.temperatures settled from the extruder hopper to the head) and at aspinning rate of 2700 m/min and constant out-put of 0.6 g/min·hole.

COMPARATIVE EXAMPLE 21 (21c) and Reference Example 21 (21r)

The comparative example 21 (21c) is the isotactic propylene homopolymer(MFR 25.8) spun as such without masterbatch added.

The reference example 21 (21r) is prepared by mixing:

-   -   94 pw of the isotactic propylene homopolymer (MFR 25.8) with    -   6 pw of the polybutene homopolymer (MFR 4, measured at 190° C.,        2.16 Kg) used for the preparation of the masterbatch.

Table 8 reports the amounts of filler and compatibilizer in the finalpolyolefin materials, the spinning process conditions, the properties ofthe material as such and those of the fibres produced with thepolyolefin material.

TABLE 8 Examples 21c 21 21r Process Step (2) Polyolefin homopolymer (MFR25.8), pw 100 94 94 polybutene homopolymer (MFR 4, pw 0 0 6 at190/2.16)Masterbatch, pw 0 6 0 Final polyolefin nanocomposite material Mineralfiller, wt %* 0 0.3 0 Compatibilizer, wt % 0 0.3 0 Spinning Process HeadTemperature ° C. 260 260 260 spinning rate m/min 2700 2700 2700 MFR ofpolyolefin component (A) 31.4 (MFR (1)) dg/min (on fibers) MFR ofpolyolefin nanocomposite 31.4 23.4 28.1 material (MFR (2)), dg/min (onfibers) MFR (1)/MFR (2) ratio (on fibers) 1 1.34 1.12 maximumspinnability speed m/min 4500 4500 4500 Titer, dtex 2.25 2.25 2.20Tenacity, cN/tex 20.6 24.4 19.9 Elongation at break, % 160 215 150

1. A polyolefin nanocomposite material comprising the followingcomponents: (A) a crystalline or semi-crystalline polyolefin resin; and(B) a nanosized mineral filler comprising a hydrotalcite, wherein theamount of the hydrotalcite is from 0.02 to 6 parts by weight per 100parts by weight of the nanocomposite material, and the ratio MFR (1)/MFR(2) of the melt flow rate value MFR (1) of component (A) to the meltflow rate value MFR (2) of the polyolefin nanocomposite material is atleast 1.02, wherein the polyolefin nanocomposite material comprises acompatibilizer, and the mineral filler and compatibilizer are dispersedin the polyolefin resin at shear mixing rates from 30 to 300 sec⁻¹, 2.The polyolefin nanocomposite material according to claim 1, wherein thecompatibilizer is a modified polyolefin selected from the groupconsisting of copolymers comprising polar monomers and polyolefinsgrafted with grafting agents comprising polar groups.
 3. A process forthe preparation of a polyolefin nanocomposite material comprising: (A) acrystalline or semi-crystalline polyolefin resin; and (B) a nanosizedmineral filler comprising a hydrotalcite, wherein the amount of thehydrotalcite is from 0.02 to 6 parts by weight per 100 parts by weightof the nanocomposite material, and the ratio MFR (1)/MFR (2) of the meltflow rate of MFR (1) of component (A) to the melt flow rate value MFR(2) of the polyolefin nanocomposite material is at least 1.02, theprocess comprising melt mixing the polyolefin resin component (A), thehydrotalcite (B) and the compatibilizer at shear mixing rates of from 30to 300 sec⁻¹, thereby forming a molten polyolefin resin.
 4. The processaccording to claim 3 further comprising one step of adding mineralfiller (B) directly to the molten polyolefin resin component (A) in thepresence of the compatibilizer, wherein the mineral filler (B) isundiluted.
 5. The process according to claim 3 further comprising thefollowing steps: 1) preparing an intercalated masterbatch by mixing apolyolefin resin (A′) wherein component (A′) can be the same as thepolyolefin resin component (A) or different, with a mineral filler (B)in the presence of a compatibilizer; and 2) mixing the intercalatedmasterbatch prepared in step (1) with the polyolefin resin component(A).
 6. The process according to claim 5, wherein the polyolefin resin(A′), used in step 1 for preparing the intercalated masterbatch, is abutene-1 homopolymer or copolymer of butene-1 with at least one otheralpha-olefin.
 7. The process according to claim 5, wherein the mineralfiller (B) is added in step 1 to the polyolefin resin when it is in themolten state.
 8. A fibre comprising the nanocomposite material accordingto claim
 1. 9. A non-woven fabric comprising the fibres of claim
 7. 10.A film comprising the nanocomposite material according to claim
 1. 11.An injection moulded article comprising the nanocomposite materialaccording to claim
 1. 12. A pipe comprising the nanocomposite materialaccording to claim 1.